From mboxrd@z Thu Jan 1 00:00:00 1970 From: AL-KERNEL To: kernel-cve@kernelcve.org Subject: [CVE-2026-74390][MODERATE 7.0] RDMA/irdma: Fix out-of-bounds write in irdma_copy_user_pgaddrs [ Upstream Date: Sat, 15 Aug 2026 15:11:16 -0400 Message-ID: MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit X-AL-KERNEL-CVE: CVE-2026-74390 X-AL-KERNEL-Priority: MODERATE 7.0 X-AL-KERNEL-Severity: MODERATE 7.0 X-AL-KERNEL-Base-Severity: MODERATE X-AL-KERNEL-KPANIC: YES X-AL-KERNEL-ActionableScore: 8 X-AL-KERNEL-ActionableScore-Lower: 6 X-AL-KERNEL-Commit: 4780f58672ee6328accd54a95f9c00683477e499 List-Id: CVE: CVE-2026-74390 Priority: MODERATE 7.0 AL-KERNEL base severity: MODERATE KPANIC flag: YES Patch: RDMA/irdma: Fix out-of-bounds write in irdma_copy_user_pgaddrs [ Upstream Commit: 4780f58672ee6328accd54a95f9c00683477e499 Upstream patch: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=4780f58672ee6328accd54a95f9c00683477e499 Original CVE announcement: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-74390 Analysis date: Sat, 15 Aug 2026 15:11:16 -0400 ActionableScore: 8 ActionableScore lower bound: 6 Actionable bucket: Strong Important candidate / Actionable Moderate at minimum Manual review required: YES Summary: A local user with access to the irdma RDMA verbs device can trigger an out-of-bounds write past the fixed pgaddrmem array during PBLE setup by providing a umem with more DMA blocks than the lvl 0 path can store, causing kernel memory corruption with at least DoS impact and plausible privilege escalation risk. ====================================================================== ABOUT THIS REPORT ====================================================================== The original Linux kernel CVE announcement for CVE-2026-74390 is available here: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-74390 The original announcement does not normally provide a security severity estimate, CVSS assessment, or enough information to determine whether the reported kernel bug represents a practically relevant security issue. This report was generated by AL-KERNEL, an AI-assisted Linux kernel vulnerability analysis system developed by Alexander Larkin. It combines an autonomous classifier with LLM-assisted technical analysis and a separate ActionableScore mechanism. The purpose of this report is to prioritize Linux kernel CVEs before manual review, identify cases that require prompt investigation, and support automatic closure of issues that are unlikely to have meaningful security impact. Published priority for this report: MODERATE 7.0 Manual review required: YES A detailed explanation of the methodology and priority rules is included at the end of this message. ====================================================================== AL-KERNEL CLASSIFICATION RESULT ====================================================================== CVE-2026-74390 MODERATE CHECK WITH IMPACT FROM ORIG NN LOW Maybe valid. Check manually. Hints by AL-KERNEL: The best (paranoid) CVSS is 'AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H';*CWE-787;*CWE-20;CWE-119;BEST CVSS score: '7.8';DESCR 'An out-of-bounds write in the RDMA/irdma user verbs path can occur because irdma_copy_user_pgaddrs copied all DMA blocks from a user umem while the lvl 0 path stores entries in the fixed size iwmr pgaddrmem array. A local process with access to the irdma RDMA device can provide a umem with more DMA blocks than the fixed lvl 0 storage can hold, which can corrupt adjacent kernel memory. For the CVSS the PR:L because triggering requires local access to RDMA user verbs or the RDMA device file, but full root privileges are not necessarily required when uverbs access is delegated to users or containers. The issue is not directly network reachable because the vulnerable operation is a local control path for memory registration or ring setup rather than remote packet processing. Impact is at least local denial of service via kernel memory corruption and in worst case may allow privilege escalation, so confidentiality, integrity, and availability are rated high.';YES REQUIRES MANUAL CHECK; ,and ActionableScore result is Strong Important candidate / Actionable Moderate at minimum (with actual score 8) YES WRITE OOB SIMPLEFIX NETWORK DMAorINTERRUPT HARDWARE KPANIC KPANIC INCREASED_TO_HIGH_BASED_ON_GUESSCVSS DECREASED_TO_MODERATE7_BASED_ON_FALSEPOSCHECKOFKP NO NO checked ====================================================================== ACTIONABLESCORE ANALYSIS ====================================================================== ActionableScore=8 ActionableScoreLower=6 ## 1. ActionableScore * Conservative score: 6 * Paranoid score: 8 * Final recommended bucket: **Strong Important candidate / Actionable Moderate at minimum**:: ## 2. Signal breakdown Conservative score: * Local unprivileged trigger: +1. A local process with access to the irdma RDMA userspace verbs device can influence the umem and ring setup path. * Constrained kernel buffer overwrite: +1. The bug is an explicit out-of-bounds write past the fixed 4 entry `iwmr->pgaddrmem` array, but the written values are DMA addresses rather than a fully arbitrary payload. * Weak LPE concern: +1. Kernel memory corruption is present, but the patch does not demonstrate target selection, reclaim, callback overwrite, or an arbitrary write primitive. * Reliable kernel crash / strong DoS: +1. Writing past a fixed kernel array can realistically corrupt adjacent state and crash the kernel. * RDMA API with DMA mapping influence: +1. The user controlled umem layout affects how many DMA block addresses are copied. * Privileged kernel/device-management memory corruption path: +1. The corruption is in an RDMA driver PBLE/PBL setup path and affects DMA-adjacent kernel metadata. * Rare / hardware-specific exposure: -1. The issue requires affected Intel irdma hardware and access to the RDMA device. Paranoid delta: * Memory corruption, strong corruption primitive: upgrade to +2. The patch explicitly fixes an out-of-bounds write in kernel memory. * Strong LPE plausibility: upgrade to +2. Local kernel OOB writes in driver object state can plausibly become privilege escalation even when the exact primitive is not demonstrated. * Confidentiality impact plausible: +1. If the corruption is exploitable as LPE, confidentiality impact follows. * Integrity impact plausible: +1. Kernel memory corruption can plausibly affect integrity in the paranoid interpretation. ## 3. Reachability analysis The bug is locally reachable through RDMA userspace verbs or related object creation paths when the system has an affected irdma device and exposes `/dev/infiniband/uverbs*` to the attacker. Full root privileges are not necessarily required in deployments where RDMA access is delegated to users, service accounts, containers, or HPC workloads. It is not directly network reachable because the vulnerable path is local memory registration or queue object setup, not remote packet processing. Namespace and container setups matter because device passthrough or delegated uverbs access can reduce the practical privilege requirement to PR:L. Call-site confidence: high. The patch includes both the vulnerable helper and the caller, showing that `lvl == 0` selects the fixed `pgaddrmem` buffer and that the old loop could exceed its length. ## 4. Severity interpretation This is not an ordinary Moderate cleanup. It is an explicit kernel out-of-bounds write in a device driver path reachable from local RDMA userspace interfaces. Realistic exploitation evidence is limited because the overwrite payload and adjacent target are not shown to be fully attacker-controlled, so the conservative score stays in Actionable Moderate range. The paranoid score is Strong Important candidate because local kernel OOB writes have a plausible LPE risk and should not be auto-closed. ## 5. One-sentence report phrase A local user with access to the irdma RDMA verbs device can trigger an out-of-bounds write past the fixed pgaddrmem array during PBLE setup by providing a umem with more DMA blocks than the lvl 0 path can store, causing kernel memory corruption with at least DoS impact and plausible privilege escalation risk. ## 6. Manual review recommendation MANUAL CHECK REQUIRED. This is an explicit kernel OOB write in an RDMA driver with local user-controlled input and plausible LPE impact, even though the exact overwrite target and payload control need manual validation. ====================================================================== UPSTREAM PATCH SUMMARY ====================================================================== Patch: RDMA/irdma: Fix out-of-bounds write in irdma_copy_user_pgaddrs [ Upstream Commit: 4780f58672ee6328accd54a95f9c00683477e499 Upstream URL: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=4780f58672ee6328accd54a95f9c00683477e499 Changed files: drivers/infiniband/hw/irdma/verbs.c Diff excerpt: Not included in this email. See the upstream URL for the full patch. Full patch: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=4780f58672ee6328accd54a95f9c00683477e499 ====================================================================== DETAILED REPORT METHODOLOGY ====================================================================== The original Linux kernel CVE announcement for CVE-2026-74390 can be found here: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-74390 The original CVE announcement normally does not include a security-level estimate. In particular, it may not contain a CVSS assessment, an impact level, or enough information to determine whether the reported bug is a practically relevant security issue. One purpose of this parallel CVE list is to provide that missing technical and prioritization information. The original goal of the AL-KERNEL project was to prioritize Linux kernel CVE analysis automatically before manual review. The system can also help identify non-security issues that may be suitable for automatic closure. This report was generated by AL-KERNEL, an AI-assisted Linux kernel vulnerability analysis system developed by Alexander Larkin. The first analysis stage combines an autonomous classifier with additional LLM-based analysis. The autonomous classifier runs locally on a CPU and is based on a backpropagation neural network. Together, these mechanisms produce a technical vulnerability description, identify likely weakness types, estimate CVSS severity, and provide input for ActionableScore. Two CVSS estimates are retained because incomplete kernel vulnerability information often permits more than one defensible interpretation: Conservative CVSS vector: Not available The Best / paranoid CVSS vector: AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H The Best / paranoid CVSS score: 7.8 The conservative vector represents a lower-impact interpretation. The Best/paranoid vector intentionally represents a plausible upper-bound interpretation and should not automatically be treated as demonstrated real-world impact. CVSS may also need to be adjusted for a particular Linux deployment, because actual reachability, privileges, enabled kernel configuration, hardware, namespaces, exposed device nodes, and other environmental conditions can differ significantly between systems. A separate ActionableScore mechanism evaluates practical remediation urgency. Its analysis may include reachability, attack prerequisites, subsystem exposure, memory-corruption characteristics, denial-of-service reliability, and possible confidentiality, integrity, or privilege-escalation impact. Conservative ActionableScore: 6 Paranoid ActionableScore: 8 The final base severity is taken directly from the second tab-separated field of the AL-KERNEL classification result. ActionableScore does not replace or independently override that final AL-KERNEL decision, and if ActionableScore adjusted impact level of ALKERNEL, then you would see self-readable flags above like INCREASED_TO_HIGH_BASED_ON_ACTIONABLESCOREHIGHEREQTHAN7. For an AL-KERNEL result of MODERATE, this report uses the following additional presentation split: ActionableScore below 5 -> MODERATE REGULAR ActionableScore 5 or more -> MODERATE 7.0 The distinction between MODERATE REGULAR and MODERATE 7.0 makes it possible to identify Moderate issues that should receive manual analysis and fixes before lower-priority MODERATE REGULAR issues. In many cases, MODERATE REGULAR fixes may wait for a later rebase or routine update. There is one override in which MODERATE REGULAR becomes MODERATE 7.0 even when the ActionableScore is below 5. When the AL-KERNEL result contains the KPANIC flag, a MODERATE result is always presented as MODERATE 7.0. The KPANIC flag selected with few regexps without usage of AI at all, so it helps to detect cases when Kernel Crash happens and similar (to filter False-Negative results from the LLM usage). KPANIC indicates that a reliable kernel crash, kernel panic, or similarly serious kernel availability impact was identified by the classification workflow. AL-KERNEL base severity for this report: MODERATE KPANIC detected for this report: YES Published priority for this report (same as in Subject): MODERATE 7.0 These results are intended to support engineering triage. They are machine-generated estimates, and cases marked for manual review should be validated by a human security engineer before final disposition. For more info read docs linked from here: https://kernelcve.org/ (and you can submit you own patch there to generate such a report for non-existant CVE-id yet). Note that in many cases this AI tool selects higher severity, than real is (means you can expect Importants instead of Moderate 7.0 or Moderates 7.0 instead of regular Moderates). If you see such cases, please use reply email interface to add additional manual analyses info to this particular CVE. And please, please, let me know when you see Lows instead of Importants or Important instead of Low (because particular for such cases I need to tune this AI tool to make it better for this one and next similar). My contact email for such notifications is alexanjelausa@gmail.com (and both send reply to CVE record itself too and see "reply" button below for howto reply).